Motor control



Oct. 5, 1965 E. HESSE MOTOR CONTROL Filed Sept. 11, 1962 FIG."2

FIG.'3

E E 0 H my E mm E MORGAN,F|NNEGAN, DURHAM 8x PINE ATTORNEYS United States Patent 3,210,625 MOTOR CONTROL Ernest Hesse, Springfield, Mass., assignor, by mesne assignments, to Whitin Machine Works, Whitinsville, Mass., a corporation of Massachusetts Filed Sept. 11, 1962, Ser. No. 222,893 8 Claims. (Cl. 3186) This invention relates to motor control means for con trolling motors employed in take-up drives and like applications where material such as filaments, fibres, wire, extruded plastics and the like are spooled.

In winding material such as yarn, and in related applications, it is frequently essential that tension factors be carefully controlled to prevent malfunctions such as breakage. These tension factors must be controllably varied in the presence of spool diameter changes which accompany winding operations and this control must be precise in view of the delicate nature of many filaments.

Of increasing importance is the further need of minimizing all mechanical handling of the yarn between production and packaging. This need is particularly acute in producing glass fibres.

It has been one common practice heretofore to provide some measure of control by employing a mechanical coupling which is in engagement with the yarn at its input end and with a motor control device, such as a rheostat, at its output end, the object being to sense yarn tension or a function thereof and to translate this into a motor control parameter. One mechanical coupling widely employed for this purpose is known as a dancer arm mechanism.

This and analogous arrangements of the prior art have serious drawbacks. The yarn is handled by the dancer mechanism contrary to many requirements; the control function has all the limitations inherent in a mechanical coupling; the motor control system which frequently operates in a potentially explosive or otherwise adverse atmosphere cannot be sealed without great difliculty.

It is to an alleviation of these shortcomings that the present invention is directed.

Accordingly, a specific object of the invention is to provide a motor control system for yarn take-up and analogous applications which provides a controllably varied motor output without dependence on external control connections to the spooling or transfer system.

A further object is to provide a motor control system for providing precise control over tension and related factors without the need for mechanically handling the yarn at intermediate points.

A still further object of the invention is to provide a self-contained motor control for yarn take-up and analogous applications which by virtue of its self-contained feature may be sealed for safe, reliable use in adverse environments.

These and other objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by rneans of the instrumentalities and combinations pointed out in the appended claims.

Briefly and generally the motor control system according to the invention provides motor control means electromagnetically controlled in response to motor current or a related parameter whereby the control means vary motor output such as torque, as a function of motor current with the result that tension or related factors are automatically regulated without the need for external couplings to the control circuit.

The invention consists in the novel parts, constructions,

arragements, combinations and improvements herein show and described.

Serving to illustrate exemplary embodiments of the invention are the drawings of which:

FIGURE 1 is a schematic diagram illustrating a control system according to the invention as employed in a yarn spooling application;

FIGURE 2 is an elevational view partly in section illustrating additional structural features of the motor control unit; and

FIGURE 3 is a schematic diagram illustrating means for selecting one of a plurality of motor control responses in accordance with application requirements.

As seen in FIGURES 1 and 2, the control system according to the invention includes a control unit generally indicated at 10 and connected between power terminals P P and P and a motor M which illustratively drives a take-up spindle 8. Between the power terminals and control unit is a three section power switch S While a three phase arrangement is shown, both single phase and two phase circuits are amenable to the control functions hereinafter described.

As embodied, the control unit includes reactor means X and X connected between the motor M and two of the power terminals P and P respectively. Capacitors C and C shunt respectively, the reactors X and X and all of these components are mounted within casing 11 which is adapted to be rendered explosion proof.

A convenient mounting arrangement is illustrated in FIGURE 2 where the coils of reactors X and X are each secured as by bolting to a base 12 securely fitted within casing 11. Capacitors C and C are also secured to the base as by a strap 13. The base also includes a flanged section to which a terminal strip 14 is connected. Case 11 has fittings 15 and 16 in the Walls of the housing for the passage of leads interconnecting the control unit, motor, power terminals and any additional circuit elements.

Means are provided for varying the reactors X and X in response to motor current. As embodied, such means comprise core elements L and L each magnetically linked to the respective reactor coil and urged into one position by resilient means embodied as a spring 18. For temperature compensation this spring includes thermally responsive material and may thus comprise a bi-metallic or other temperature responsive structure.

As seen in FIGURE 2, the core elements L and L are disposed to slide axially within the cores of the respective reactors. Both L and L are resiliently urged in a direction out of magnetic engagement with the respective coil by the spring 18 one end of which abuts a stop collar 19 on a rod 20 secured to base 12 and the other end of which engages a washer 21 slidable on rod 20 and hearing against a cross link 22 similarly slidable on 20. The cross link is secured at its ends to the respective core elements L and L as by pinning and further includes a pair of stop adjustments 23 threadably installed therein and adapted to limit travel of the elements L and L; by engagement with the wall of casing 11.

In a typical application, system elements are designed such that with no current drawn by motor M, the spring 18 displaces the reactance varying elements L and L into the position of maximum remoteness from coils X and X When motor M operates, the resultant currents flowing in X and X provide an electromagnetic attraction with respect to L and L tending to draw these elements, against the force of spring 18, into closer magnetic re lationship with the associated coil. This change of position produces a resultant change in coil reactance and a related change in motor current. In the presence of this interdependence, a point of equilibrium is reached, generally with L and L at some intermediate position for a given motor load condition.

If, after initial equilibrium is reached, some external condition such as an increase in spool diameter, tends to change motor current, there will be a corresponding change in the positions of L and L producing a corresponding change in the reactances of X and X Hence the motor current and tension will tend toward restoration to the equilibrium value.

This self-regulating response, which is independent of external connections to the yarn transport mechanisms, may be adjusted to provide various characteristics, as by shaping of the core elements L and L e.g., with the aid of holes 25, or, as seen in FIGURE 3, by providing switching means 30a, 30b, for selectively shorting and disabling portions of each coil X and X Thus, the self-regulating characteristics may be adapted to provide various regulated tension characteristics.

In some applications such as in fast starting modes, it is desirable to bypass the control reactors. This may be achieved by shunting the reactors with respective switches S as shown in FIGURE 1. When closed, these switches disable the control function.

The invention is not limited to the specific mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

What is claimed is:

1. In a material Winding apparatus, a self-contained motor control apparatus adapted to regulate motor means for driving material take-up arrangements and the like so as to provide a constant tension on material being wound by said take-up arrangement, comprising reactance means operatively connected in the circuit of said motor means for controlling the current in said circuit and reactance varying means physically isolated from the output side of said motor means and responsive to the electromagnetic forces generated by the flow of current through said reactance means for varying said reactance in response to changes in said current to thereby regulate said cur-rent so as to vary the torque in said motor means to maintain a constant tension on said material.

2. Apparatus according to claim 1 in Which said reactance varying means comprise means in magnetically attractive and resiliently opposed relation to said reactance means.

3. Apparatus according to claim 1 in which said reactance varying means include means for varying said electromagnetic response as a function of temperature.

4. Apparatus according to claim 2 in which said means in magnetically attractive relation comprise core mean-s movable with respect to said reactance means.

5. Apparatus according to claim 2 in which said reactance means comprise an inductive coil and said magnetically attractive means comprise core means axially movable with respect to said coil.

6. Apparatus according to claim 4 in which said core means are of non-uniform shape for varying said current regulation.

7. Apparatus according to claim 4 including a spring coupled to said core means for providing said resilient opposition and means for varying the resiliency of said spring as a function of temperature.

8. Apparatus according to claim 1 including explosionproof control means for housing said apparatus.

References Cited by the Examiner UNITED STATES PATENTS 674,942 5/01 Sprong 323- 1,596,505 8/26 Moore 3233 1,894,928 1/ 33 Wesche 318228 2,187,523 1/40 Pelikan 323-5 2,339,939 1/44 Michel 3186 X 2,754,459 7/56 Keith et al. 3186 ORIS L. RADER, Primary Examiner. 

1. IN A MATERIAL WINDING APPARATUS, A SELF-CONTAINED MOTOR CONTROL APPARATUS ADAPTED TO REGUALTE MOTOR MEANS FOR DRIVING MATERIAL TAKE-UP ARRANGEMENTS AND THE LIKE SO AS TO PROVIDE A CONSTANT TENSION ON MATERIAL BEING WOUND BY SAID TAKE-UP ARRANGEMENT, COMPRISING REACTANCE MEANS OPERATIVELY CONNECTED IN THE CIRCUIT OF SAID MOTOR MEANS FOR CONTROLLING THE CURRENT IN SAID CIRCUIT AND REACTANCE VARYING MEANS PHYSICALLY ISOLATED FROM THE OUTPUT SIDE OF SAID MOTOR MEANS AND RESPONSIVE TO THE ELECTROMAGNETIC FORCES GENERATED BY THE FLOW OF CURRENT THROUGH SAID REACTANCE MEANS FOR VARYING SAID REACTANCE IN RESPONSE TO CHANGES IN SAID CURRENT TO THEREBY REGULATE SAID CURRENT SO AS TO VARY THE TORQUE IN SAID MOTOR MEANS TO MAINTAIN A CONSTANT TENSION ON SAID MATERIAL. 